Isolation of Antipodal (−)-Versicolamide B and Notoamides L−N from a Marine-Derived Aspergillus sp.

Antipodal (−)-versicolamide B and notoamides L−N were isolated from a marine-derived Aspergillus sp. The possible biosynthetic pathway of enantiomeric pairs of notoamide B and versicolamide B are proposed. Notoamide L is the first metabolite containing 25 carbons in the related prenylated indole alkaloids. Notoamide M is potentially a precursor to the proposed azadiene species involved in the putative intramolecular Diels−Alder reaction in the biogenesis of the bicyclo[2.2.2]diazaoctane ring system.